AC&C/SPARC Ozone Database for CMIP5

This website decribes the AC&C / SPARC Ozone Database that has been created in support of CMIP5. It covers the period 1850 to 2100 and can be used as ozone forcing for CMIP5 models that do not include interactive chemistry. The ozonedatabase is provided in CF compliant netCDF format (T3M fields: Monthly-mean 3-d atmosphere data (longitude, latitude, pressure, time:month) ).

Contact for questions: Veronika Eyring, Irene Cionni (DLR, Germany), Jean-Francois Lamarque (NCAR, USA), and Bill Randel (NCAR, USA)

A. The historical part of the AC&C/SPARC ozone database covering the period 1850 to 2009 is now available at the CMIP5 website at PCMDI. The historical ozone data combine separate stratospheric and tropospheric data sources:

1. The stratospheric data are constructed using a multiple linear regression analysis of SAGE I+II satellite observations and polar ozonesonde measurements for the period 1979-2005, as described in Randel and Wu (JGR, 2007). The regression includes terms representing equivalent effective stratospheric chlorine (EESC) and 11-year solar cycle variability.
   
2. The stratospheric time series are extended backwards to 1850 based on the regression fits combined with extended proxy times series of EESC and solar variability.
   
3. Tropospheric data are derived from model simulations. The tropospheric ozone simulations were performed using the chemistry-climate models Community Atmosphere Model(CAM) version 3.5 and the NASA-GISS PUCCINI model. Both models simulate tropospheric and stratospheric chemistry with feedback to the radiation and were driven by the recently available historical (1850-2000) emissions succintly described in Lamarque et al. (IGAC Newsletter, May 2009). Emissions are kept constant from 2000 onwards in both simulations. In addition, CAM was using sea-surface temperatures (SSTs) from a previous CCSM3 simulation while the NASA-GISS model used observed SSTs (Hadley Centre dataset of Rayner et al., JGR, 2003). The simulation for CAM was a full transient 1850-2005 (after a 10-year spinup at 1850) while the NASA-GISS model performed snapshots every 20 years from 1850 to 1930 and every 10 years thereafter, with data taken from the last 6 years of 8 year simulations. For the climatology, decadal averages were performed for each model, then the NASA-GISS results were interpolated to the CAM vertical grid and an average of both was taken. This average field represents the tropospheric ozone field in the climatology.
   
4. The stratospheric and tropospheric data are combined by simply merging the two data sets across the climatological tropopause, to produce a smooth final data set. Example plots are available below.

FINAL VERSION RELEASED ON 22 SEP 2009

B. The future part of the AC&C/SPARC ozone database covering the period 2010 to 2099  is now available at the CMIP5 website at PCMDI.

The future timeseries is a seamless extension of the historical database (merged in the year 2009), so that the entire time series (1850-2100) can be used as ozone forcing for climate models that do not include interactive chemistry. The future ozone timeseries combines separate stratospheric and tropospheric data sources: (1) The stratospheric ozone projections are taken from the future reference simulations (REF-B2) of the 13 CCMs that performed a future simulation until 2100 under the SRES A1b GHG scenario and the A1 adjusted halogen scenario in CCMVal-2 (see Chapter 9 of the SPARC CCMVal Report at http://www.atmosp.physics.utoronto.ca/SPARC). In the stratosphere, the multi-model mean of the REF-B2 simulations is used in all RCP scenarios (i.e. stratospheric ozone in this database doesn’t vary among the RCPs). (2) The future tropospheric ozone time series continues the historical CAM3.5 simulation until 2100 using the four different Representative Concentration Pathways (RCPs) that were generated by Integrated Assessment Models (IAMs) and were harmonized with the historical emissions from Lamarque et al. (ACP, 2010) in both amplitude and geographical distribution. Since RCP based simulations from an Atmosphere-Ocean climate model were not available when these runs were started, SSTs/SICs from SRES simulations closest to the RCP GHG scenarios were used. (3) As in the historical part, the future stratospheric and tropospheric data are combined by simply merging the two data sets across the climatological tropopause, to produce a smooth final data set. Citation: Cionni et al. (2010), see below."

C. Reference. A paper that desribes the AC&C/SPARC ozone database has now been published in ACPD and is open for Interactive Public Discussion until 02 Jun 2011:

Cionni, I., V. Eyring, J. F. Lamarque, W. J. Randel, D. S. Stevenson, F. Wu, G. E. Bodeker, T. G. Shepherd, D. T. Shindell, and D. W. Waugh, Ozone database in support of CMIP5 simulations: results and corresponding radiative forcing, Atmos. Chem. Phys. Discuss., 11, 10875-10933, doi:10.5194/acpd-11-10875-2011, 2011.